Signaling apparatus



Jan. 9, 1945.

J. T. NEISWINTER SIGNALING APPARATUS Filed Dec. 23, 1941 INVENTQRJZT/V/ezswzner BY TTORNEY .signed to him. i

Patented Jan. 9, 1945 STATE-S1, -PAT-EN'T OFFICE I v 2,367,042 eSIGNALING APPARATUS I f v James T. Neis winter, South Orange, N. J., as-

si'gnor to American Telephone and Telegraph Company, a corporation ofNew York V Application Dec mber 23, 1941', Serial- No. 424,105 12 Claims.r01. n -38 0) 7,- This invention relates signaling systems and,

more particularly, tosystems employing apparatus for producing modulatedcurrents to be trans mitted to various partiesrconn ected to a telephoneline for ringing or other purposes.

. One form of ringing system in use :at present for ringing any oneof aplurality of partieszconnected to a telephone line involves thetransmission of a ringing current consisting of a predetermined Inumber'of dots and dashes which are simultaneously transmitted toall ofthe parties, the'ringing current-beingrendered audiblesignaling'apparatus, but the apparatus for producing speech or likesignals as well as apparatus for, responding to the speech or likesignals will not be shown.

Referring. to the drawing, one of a number of subscribersistations isshown including, among other things, a dial D-having a contact'which isshown in its normal or closedjposition. The subscribers station'isconnected bya telephone cirat each partys station. The combination ofdots and. dashes assigned to any one of the partiesis different fromthat assigned to any other. party.

Each party will therefore hear every ringing signal transmitted over theline toany oitheother parties and the only party who willansw'er thecall will be the onewhose ringingcode has been received. This form ofringing system which cuit E'to the central ofiice; At the central ofiicethere islocated a filter F, a vacuum tube amphfier VD, a relay V0, oneof the windings of which is connected to the plate circuit of the vacuumtube'VD -a relayvi which is connected to one of the contacts'ofthe'relay Vothrough a circuit including a condenser; CA and a resistorZa, and

, includes a condenser CM, a gas tube VM, a relay may be arranged sothat any party may be rung by any one of the other parties or by thecentral ofiice operator requiresall of the parties ,tolisten to all ofthe codes received so that each party may be ready to. respond only tothe code, as-

office to respond to the manipulations'of the dial I at anysubscribersoffices. In the proposed arrangement, each dial may be'operateda'predemoreselective and posi termined number of times, each dialoperation being employed to produce a number of clicks or.

pulses on the telephone circuit, the number of clicks orpulsescorresponding-to the number dialed. At thecentral office apredetermined harmonic, of the pulses produced by the dial will beselected and caused to operate a relay for an interval of time whichisdiiierent for ,the numbersto be dialed; If'the number 0 is dialed, for

example, the relay will be operated fora longer interval of time than ifthe number 5 is dialed. The repeated operations of the relay may then becaused tooperate a selective circuit for ringing any one of the variousparties to the exclusion of all of the other parties.

This invention will be better understood from the detailed descriptionhereinafter following, when read in connection-with the accompanying twoparallel circuits which are connected to the two' contacts of the relayV1. One of these parallel circuits includes a condenser CS, a gas tubeVS, and a relay S. The other parallel circuit a condenser CL, a gas tubeVL and a relay L.

The-winding'of relay L is also connected to one of the contacts of therelay S which is in the other"parallelbranchJ The upper terminal ofcondenser CL is connected to another of the contacts of relay S. Relay Lmay be employed to control a relay N.

When the dial D at the subscribers station is operated in the usual wayfordialing, let us say, numbers 5 or 0, the arrangement will act inresponse' to the dial. operations to energize the winding of the relay Lat the-central oln'ce, the relay L being operated for either of thenumbers dialed. The circuit may be adjusted so that the operation of therelay L when'the digit 5 is dialed will take place for an interval "oftime as, for example, two-tenths of a second. The relay L will beoperated for about seven-tenths of a second when the digit 0 is dialed.

When dialing No. 1, for example, the primary circuit or transformer Awill be opened once and closedonce bythe contacts of dial D. Upon the oftransformer A upon the closure of the primary circuit. Each of the twosurges of current in the primary of transformerA will produc acomdrawing which illustrates thedialing apparatus at each subscrib'ersstation and apparatus at the central omce whichwill respond to the dialoper'ations.-Thedrawingshows only the dial or plete and independentpulse of current in the secondaryof transformer A. Thus by dialing No.1, two complete pulses of current will be transmitted by transformer-,Ato line E. Hence by dialing No. 5, ten complete pulses .of current willbe transmitted over line E. Furthermore,

by dialing No. (which is the equivalent of dialing a No. twenty completepulses of current will be transmitted over line E. These pulses ofcurrent are, of course, not pure sine waves, but transients. 'As thedial D is of the type which is generally timed to produce these twentypulses in about one second, the transients produced and transmitted overline E occur at the rate of twenty per second. Similar transients areproduced upon dialing any other number. However, 10

the number of transients produced and transmitted over line E willsimply be twice the number dialed by dial D. Hence when dialing N055,ten transients will be produced and transmitted over line E, and theseten transients'will occur} within about one-half of a second. v

The filter F at the central ol'fice may comprise one or moreanti-resonant circuits similar to the one shown, the anti-resonantcircuit orcircuits being tuned to, for example, 1000 cycles-which maybecon'sidered to be the fiftieth harmonic of the 'pulses'produced by thedial. The vfilter F will transmit the 1000 cycle harmonic to the tube-VDto be amplified thereby. The :upper winding of relay V0 which is a.polar relay will receive the 1000 cycle current which is interrupted atthe cycle rate by the dial contact and the armature of the relay V0 willtherefore operate and release at the 20 cycle rate in accordance withthe 1000 cycle current which traverses its Winding.

Thus the relay Vo will operate and release once for each dial click orpulse. Inasmuch as two clicks orpulses are produced for each unit of thenumber dialed, as already stated, the relay V0 will operate twice foreach unit ofthe number dialed. It will be shown hereinafter that thecircuit interconnecting the armature of relay V0 and the winding ofrelay L is set up. so that the dial clicks or'pulses may operate therelay L for .difierent intervalsof time, the intervals depend ing uponthe number dialed. The interposed circuit is also arranged so thatspeech and other extraneous voltages will be unable to actuate the relayL.

During the idle condition of the circuit the l contact'of the dial D isclosed and no current will be flowing over the telephone circuit RelayV0 will be held released by the bias current con tinually traversingthelower Winding of relay V0, the armature of relay V0 resting upon itscontact 1 S asshown inthe drawing. No current will be flowing throughthe winding of the relay V1, its armature also resting against itscontact S. .The condenser CS will -however, be charged to the voltage ofthe battery 131.. This voltage wi11=be hi her than that required toionize the gas between the input or control electrodes of the tube VSand, hence, the gas between these electrodes will be ionized. The relayS will be energized by the flow of current from battery 32 through acircuit completed through the armature and contact S of relay V0, thewinding of relay S, the armature designated I of relay S and its makecontact and ground. With the winding of relay S energized, ground willbe connected to theanode of tube VS by armature l' of relay S and,hence, no current will flow through the output circuit of tube 'VS. Theoperation of relay S transfers the flow of current from battery 32(through the winding of relay S) to ground so electrode will beconnected toground through the armature 2. of relay S and its makecontact.

- With condenser CL discharged, the tube VL will be deionized and,therefore, the relay L will be released. I Relay N will also be releasedand lamp P extinguished. Both tubes VM and VL are deionized for thefurther reason that plate voltage -from batteryT-Bncannot reach thesetubes, the

" tactof armature 30f relay S.

During the idle condition of the circuit, more- Assume now that the dialD of the subscribers station is rotated in a clockwise direction fordialing. any. desired .digitzand thatit is then released so that thedial may rotate in a counterclockwise idirection to open and close itscontact several times dependingon the number dialed. As thedial':contact opens, it produces a click which interrupts the currentflow overthe primary winding of transformer A. The interruption of-the primarycircuit will induce a current in the secondary circuit which is of afrequency dependent upon the constants of the dial apparatus. as alreadystated. With .a standard dial the secondary ofthe transformer. of thecircuit will have induced therein a 20 cycle current along withitsnumerous harmonies.- The fundamental andall harmonics will besuppressed by the filter F except/the fiftieth harmonic which is of 1000cycles, .the .latter current being then transmitted to the vacuum tubeVD and'amplified thereby. The amplified current will flow throughitheupper or operating' winding-of the relay V0. This current willproduceia'magnetic effect in the upper or operating'winding of relay V0to' overcome the opposing magnetic effect of the biasing current flowingthroughthelower-winding of relay V0 and therebycause the armature of therelay to move to its contact M. The closure of contact M bythe'armatureof relay Vo will then allow current toflow frombattery B2 through theimpedance Zr and through the winding of relay V1, thereby causingthe:armature of relay V1 to close its contact M. At the same time the relayS will become releasedldue tothe opening of the circuit between batteryB2 andthe winding of relay S 'denserCS will be grounded and thecondenser will then. discharge so that the gas between the input orcontrol electrodesof'. tube VS will become deionized. Moreover,the-removal of ground from the upper plate-0f condenser CM upon theoperation -.of relay Vi will allow condenser GM to become chargedbycurrent supplied by battery Ba. Upon the release .of the relay S thepositive potential of-battery B4 will be applied through the (armature 3.of the relayS and th Winding of relay M .totheanode of tube VM.However, the charge'on condenser CM will not be raised to the valuerequired to ionize .the gas between the input electrodes-of tube VMunless relay V1 operates for a longer timethan the time required for oneclick orypulse of a standard dial. Hence relay M will remain unoperated.The release of relay S also removes ground from the upper plate ofcondenser -.C L theretofore provided throughthe armature .2 ofrelay'S,thereby allowfurther described.

ing condenser CL also. tocharge. A positive potential is likewiseapplied by battery B4 to'the anode of tube VL through the winding ofrelay L, but for similar reasons tub VL will not be fired and relay Lwill therefore remain released.

: At the termination of the first click or pulseof the dial, currentwill cease to flow through the primary winding of transformer A and,hence,

and insufficient to overcome the biasing effect of the currenttraversing the lower winding of this relay and hence relay V will'remainreleased. While relay V0 is released, battery B2 will be disconnectedfrom the winding of relay V1, thereby releasing relay Vi, the armatureof relay V1 then a closing its contact S. At the same time the positivepotential of battery B2 will be applied to the anode of tube VS throughthe armature and contact S of relay V0 and the winding of relay S. As

the armature of relay V1 also leaves its'contact M the condenser CS-willthen be charged by current supplied by battery B1, but the tubeVS willremain deionized because the voltage on condenser CS will beinsufficient in the time after the first click or pulse to reach thevalue re- F quired to ionize the gas between the input electrodes oftube VS.- Also the condenser CM will be discharged through the circuitprovided by the armature and contact S of relay V1. v

As the dial contact becomes closed at the end of the first unit of thenumber;dialed,'the dial remaining in rotation thereafter, another clickor pulse will be produced. This will result in the transmission throughthe filter F of a'similar 1000 cycle current. The armature of relay'Vowill again move to its contact M and the cycle of events similar to thatalready described for the opening of the dial contact which produced alike current will be repeated, but this need-not be The same series" ofevents will take place with each? opening and closure of the contacts ofthe dial D as the dial rotates in a counter-clockwise direction after itis released. It will be observed, however, that the relay S, thoughnormally operated in the idle condition, becomes released as the dialrotates to close its contact and relay S stays released throughout themovement of the dial.

After a predetermined intervalof time as, for

- example, about three-tenths of, a second after the dial D has firstopened its contact, the condenser CL will reach a voltage upon chargewhichis suflicient to ionize the gas within the control gap of the'tubeVLF This time interval is dependent upon the size of the condenser, thepotential of the battery B5 and other circuit constants. vAfter the tubeVL becomes fired the relay L will become operated due to the flow ofcurrent from battery B4 through the circuit established by armature 3 ofrelay S after relay S has become released. The relay Lwvill remainoperated until dial D has come to rest and finally closed its contact. v

Upon the operation of relay L, relay N will be operated, currentbeing'supplied to the winding.

of relay N fromv battery B7 throughthe lower armature and its frontcontact. In. operating, relay N becomes locked in its operated position,the-locking circuit comprising battery E8, the upper armatureand makecontactof relay N, coninafter.

tact X1 of jack J,.the winding of relay N and ground- The armature ofrelay N may also be used to complete a circuit to lamp P to apprise theoperator that the subscriber has signaled her.

The operator may then insert her plug into jack J toconnect her cord toline R. The insertion of her plug into jack J momentarily breaks theholding circuit for relay N and, therefore, the latter relay releases,extinguishing lamp P, The

subsequent'reoperation of relay N makes possible a recall signal byre-illuminating lamp P while the operators plug is still in jack J.

When the dial D closes'its contact at the end of its rotation, the relayV0 will thereafter become released, which in turn will cause the relayV1- to become released. The relay of relay V0 will allow the positivepotential of battery B2 to be applied through the armature and contact Sof relay V0 and the winding of relay S to the anode of tube VS. As thecharge on'condenser CS reaches a sufiicient value, the tube VS willbecome ionized, the ionization occurring after a predetermined intervalof time as, for example, about 35 milliseconds after the dial has cometo rest. As the tube VS becomes ionized current will flow through thewinding of relay S, causing its operation. But as relay S operates, itconnects the anode of tube VS to ground through its armature I anditsmake contact The armature of relay S then opens the circuit betweenbattery '34 and the anodes of tubes VL and VM, causing both tubes tobecome deionized. As tube VL becomes extinguished, the relay L willbecome released and remain released thereafter. Thus the circuitarrangement will be returned to its idle condition.

M It will be observed that the arrangement at the central ofliceincludes a filter F which is tuned to about'lOOO cyclesand a networkinterposed between the filter F and relay L which acts like a 20 cyclefilter. This combination of circuits is designed to prevent voicecurrents from operating the relay L, as will be explained here- Thenetwork interposed between filter F and relay Ldistinguishesbetween theseries of clicks or pulses produced by dialing the number 5, forexample, and the series of clicks or pulses produced by dialing 0, thedistinction being based upon the fact that the first series of clicks orpulses-which may be approximately five-tenths of a second longmayoperate relay 'L for, let us ,say, about two-tenths of a second, whilethe second series of clicks 0r pulseswhich may last about one second-mayoperate the relay L for about seven-tenths of a second.

It has been pointed out hereinabove that relay V1 is operated inresponse'to each operation of relay V0. The condenser CA is interposedbe tween the armature of relay Va and the winding of relay V1 as alreadynoted. This condenser in discharging holds the relay V1 operated for afew milliseconds after relay V0 has released. The value of the hold-overfeature is such that if the relay V0 operates faster than say 25 timesper second, the winding of relay V1 will then receive suflicient currentfrom condenser CA to remain in an operated condition during the repeatedreleases of relay V0. For vibrations of the armature relay V1 will fixthe lower limit of thefilter net-' work as will be explainedhereinafter.

- per second, the interval betweenthe clicksduring which time, the relayV1 is released-Will be long enough to permit the condenser CS to becharged by current from battery B1 to a voltage sufficient to ionize thecontrol gap of the tube VS. When this happens the relay S will becomeoperated, thereby grounding the condenser CL through the armature 2 ofrelay S. Hence for clicks or pulses of such a slow rate the relay L willremain released.

The arrangement is thus tailored to fit the series of pulses transmittedover the telephone circuit E and applied to the operating winding ofrelay V0. Whenever the interval between the clicks or pulses is toolong'the tube-VS Will become ionized and prevent relay L from operating.On the other hand, whenever the durations of the clicks or pulses aretoo long, the tube VM will become ionized and likewise prevent relay Lfrom operating. Whenever the Spaces between the clicks or pulses andtheir durations are both too short-Which will be the case for a fastdial or for any low frequency effect induced in the telephone circuitEthe relay V1 will remain operated and tube VM Will become ionized. Thiswill result'in maintaining relay L released.

When voice currents reach the telephone circuit it will happen inpractically all cases that the pause between the syllables will be longenough to cause tube VS to become ionized. On the other hand, one of thesyllables of the speech currents may be so prolonged as to cause thetube VM to become ionized before the interval of .time such asthree-tenths of a second, which is required to elapse before relay Loperates. In either case relay L Will not become operated.

It has been shown hereinabove that with each operation of the dial therelay L will be operated for an interval of time which is either long orshort depending upon the number dialed. If the dial were operated fourtimes, for example, the relay L will then be operated four times and ineach case the duration of the operation of relay L will depend upon thenumber dialed. Thus the dial may be successively operated to produce anydesired combinations of long and short pulses.

The condenser CM and tube VM in the upper branch of the arrangement areemployed to prevent currents derived from the clicks or pulses fromoperating relay L if these currents last longer than about 20milliseconds. The condenser CS and tube VS in the lower branch of thearrangement are employed to prevent pulsesderived from the clicks orpulses from operating relay L if the intervals between the clicks orpulses last longer than about 35 milliseconds. Relay L is thus protectedagainstall pulses except those derived from suitable dial clicks fromwhich 1000 cycle current interrupted about 20 times per second isderived.

shown) which may be connected to conductors y1y2, the voltage beingapplied for an interval I of time depending upon the length of theoperation of relay L. In the latter situation relay N and its relatedcircuits maybe omitted. Apparatus for responding to any such series orcombinationof three, four, or more pulses-s-which may be any desiredcombination of long and short pulses-are shown and described inapplicants copending applications, Serial Nos. 373,573 and 373,574,filed January 8, 1941, and Serial No. 399,782, filed June '26, 1941, nowrespectively, Patents 2,334,574, 2,334,575 and 2,300,003 and theselecting or switching circuit there shown may be considered as part ofthis specification. The selecting or switching circuit will be connectedto conductors 111 and 112.

The arrangement of this invention may therefore be used either torespond to dial clicks or pulses to operate relays L and N andilluminate lamp P to apprise the central office operator that a call isbeing transmitted or (Without relay N and lamp P) to apply voltage anumber of times to conductors 111 and 212 to produce pulses to operate aselective circuit for connecting the subscriber to any one of aplurality of diiTerent lines. In either case the control of the circuitis practically entirely exercised by the subscriber in manipulating thedial.

.While this invention has been shown and described in certain particularembodiments merely for the purpose of illustration, it will beunderstood that the general principles of this in-. vention may beapplied to other and widely varied organizations without departing fromthe spirit of the invention and the scope of the appended claims.

What is claimed is:

1. In a signaling system, the combination of a pulsing device, a sourceof direct current, a transformer having its primary winding connected inseries with said source of current and said pulsing device, meansresponsive to the operation of said pulsing device to produce in thesecondary Winding of said transformer a series of pulses of alternatingcurrent of a frequency which is harmonically related to the number ofcurrent spurts produced by said pulsing device in 'the primary windingof said transformer, one

pulse of said alternating current being produced in the secondarywinding by the interruption of the flow of current from said source inthe primary winding and another pulse by the reconnection of said sourceto said primary winding, means responsive to the ulses of alternatingcurrent in the secondary winding to produce a pulse of direct current,said latter means including means to prolong the pulse of direct currentso that its length corresponds to the number of alternating currentpulses in the secondary winding, and -a translating device responsive tosaid pulse of direct current.

2. In a signaling system, the combination of a dial having a contactwhich may be repeatedly opened and closed, a source of direct currentvoltage, a transformer having its primary winding connected in serieswith said dial-and said sourceof voltage'so that a plurality of'spurtsof current may flow in the primary winding with 'each operation of saiddial, means responsive to the repeated opening and closing of thecontact of said dial to derive fromsaid spurts of current a seriesofpulses of alternatingcurrents said alternating currents beingharmonicallyre lated to the number of said spurts of current produced bysaid dial device, means responsiveto the pulses of alternating currentin the secondary windingto obtain a single pulse of direct current of aduration which corresponds to the number of alternating current pulses,and apparatus controlled by said pulse of direct current.

3. Ina signaling system, the combination of a dial having a contactwhich may be repeatedly opened and closedf a source of unidirectionalvoltage, a transformer having its primary winding connected in serieswith said source of voltage and said dial so that a plurality of spurtsof current will traverse the primary winding with each operation Ofsaiddial, means responsive tothe repeated operations of said dial to derive'5. In a signaling system, the combination of i a dial having a contactwhich may be opened and closed one or more tim'es'during each operafromsaid spurts of current a plurality of groups of pulses of alternatingcurrent of a frequency which is.a harmonic of the number of said spurtsof current per second, a pulse of alternating current being producedinthe secondary winding 01 said transformer by the interruption of theflow of current from said source of voltage to said primary winding andanother pulse being produced in said secondary winding by a reconnectionof said source of voltage to said primary winding, means responsive toeaclr group of pulses of alternating current to obtain a pulse of directcurrent, and a circuit controlled by said pulse of direct current.

' 4. In a signaling system, the combination of a dial having a contactwhich may be opened and closed during each operation of the dial, a

source of unidirectional voltage, a transformer having itsprimarywinding connected in series with said dial and said source ofvoltage so as to produce a plurality of spurts of current in the primarywinding of said transformer with each.

operation of said dial, each operation of said dial opening and closingsaid contact one or more times, means responsive to the repeatedoperations of said dial to produce in the secondary,

winding of said transformer a plurality of groups of pulses. ofalternating current of a frequency which is harmonically related to thenumber of said spurts of current per second, a pulse of alternatingcurrent being produced in the secondary winding upon the interruption ofthe flow of current from said source of voltage through the primarywinding of said transformer and another of said pulses being produced inthe secondary winding of the transformer by the resumption of the flowof current from said source through the primary winding of saidtransformer, the number of pulses of alternating current in each groupbeing determined by the number of times the dial contact is opened andclosed in each operation of the dial, means responsive to.

of current in the primary winding of said transformer with eachoperation of said dial, said. spurts of current in-the primary windingofsaid transformer producing a plurality of pulses of alternatingcurrent in the secondary winding of said transformer, a pulse ofalternating current being produced in' the secondary winding of saidtransformer upon each interruption of the flow of current from saidsource through said primary winding and another pulse being producedupon each reconnection of said source with said primary winding,meansfor obtaining from said pulses of alternating current in thesecondary winding of said transformer pulses of a predetermined harmonicof said alternating current in the voice frequency range, and meansresponsive to the pulses of said harmonic current to obtain a pulse ofdirect current of a length which is proportional to the number of pulsesof the harmonic current.

6. In a signaling system, the combination of a dial having a contactvWhich may be opened and closed one or more times during each operationthereof, a source of unidirectional voltage, a transformer having aprimary winding connected in series with said dial and said source ofvoltage so as to produce a plurality of spurts of current in theprimarywinding of said trans: former with each operation of said dial,said spurts of current in the primary winding of said transformerproducing a plurality of pulses of alternating current in the secondarywinding of said transformer, a pulse of alternating-current beingproduced inthe secondary winding with each opening of the circuit ofsaid source of voltage and said primary winding and another pulse ofalternating current being produced in the secondary winding with eachreconnection of said source of voltage and said. primary winding,meansfor-obtaining from said pulses of alternatingcurrent in thesecondary winding of said,

transformer pulses of a predetermined harmonic of saidalternatingcurrent within the voice frequency range, means responsive tothe pulses of.

said harmonic current to obtain a pulse of direct current of a lengthwhich is proportional to the number of pulsesof harmonic-current, and acircuit controlled by said pulse of direct current.

, 7; In a signaling system, the combination of a subscribers station, acentral omce, and a line interconnecting said subscribers station andsaid central ofiice, the subscriber's station including a dial having acontact which may be opened and closed one or more times during eachoperation thereof, a source of unidirectional voltage, and a transformerhaving its primary winding connected in series with said source ofvoltage and said dial so as to produce a plurality of spurts of currentin the primary winding of said transformer with each operation of saiddial, the secondary winding of said transformer being connected to saidline, said spurts of current in the primary winding of said transformerproducing in the secondary winding of said transformer pulses ofalternating current of a frequency which is harmonically related to therate at which said spurts of current are produced in the primary windingQ said transformer, the number of pulses of V alternating current beingdetermined by thevnumber of times-the contact of said dial is opened andclosed during any operation thereof, said pulses of alternating currentbeing transmitted over said line to the central oifice, said centralofiice including means responsive to received pulses of alternatingcurrent to Obtain a pulse of direct current of a length which isproportional to the number ofpulses of alternating current, and acircuit controlled by said pulse of direct current.

8. In a signaling system, the combination of a dial having a contactwhich may be opened and closed any desired number of times, means ressponsive to each opening and closing of the dial contact to produce two.pulses of alternating current, first and second condensers, means forcharging the first condenser to a predetermined voltage whenever eachpulse lasts longer than a predetermined interval of time, means forcharging the second condenser to a predetermined voltage when theintervals between the pulses exceed a predetermined interval or time, acircuit to which voltage may be capplied,and means for preventing saidvoltage from being applied to said circuit whenever the charge on eitherof said o nse s eac es s d red te mined a e- 9. n a gna n s s em, he m nn of a dial having a contact which may be opened and closedany desirednumber of times, means responsive to each opening of said dial contactto produce a pulse of alternating current, means responsive to eachclosure of the dial contact to produce another pulse of alternatingcurrent, first and second condensers, means for charging the firstcondenser to a predetermined voltage whenever any pulse lasts longerthan a predetermined interval of time, means for charging the secondcondenser to a predetermined voltage whenever the intervals between thepulses last longer than a predetermined interval of time, a translatingdevice, means for operating said translating device only when thevoltages on said condensers do not reach the predetermined values,and'means for preventing'the operation of said translatingdevice'whenever the voltage on either condenser exceeds thepredetermined value.

10. In a signaling system, the'eombination of adevice'having a contactwhich may be opened and closed any desired number of times, meansresponsive'to the operation of said device to'produce a plurality ofpulses of alternating current,

: means for operating said translating device in response to said pulsesof alternating current, and means for preventing the operation of saidtranslating device whenever either of the gas tubes has been fired.

1.1. In a signaling system, the combination of means for producing apredetermined number of direct current pulses in regular succession, atransformer having its. primary winding connected in series with saidpulse producing means, a pulseof alternating current being produced inthe secondary winding of said transformer from each direct current pulsetogether with the harmonies of said alternating current, a lineconnected to the secondary winding of the transformer for transmittingsaid alternating current pulses and the harmonics, afilter for selectingfrom. the received pulses only those pulses which are of a predeterminedharmonic of the alternating current to the, exclusion ,of all otherourrents, a relay, means for actuating said relay in response to thereceipt of said selected harmonic, and means interposed between saidfilter and said relay to prevent the operation of said relay in responseto currents other than pulses of the selected harmonic.

12. The combination of means for producing alternating currentinterrupted at regular intervals, first and second condensers, first andsecond gas tubes controlled respectively by said condensers, meansresponsive to the length of each pulse of alternating current to chargesaid first condenser, means for firing said first gas tube when thechargepn said first condenser exceeds a predetermined value, meansresponsive to the interval between successive pulses of alternatingfirst and second condensers, first and second gasa.

for firing said second gas'tube when the charge on said second condenserexceeds a predetermined value, a translating device, means responsive tothe pulses of alternating current to operate said translating device,and means responsive to the-firing of either gas tube. for preventingthe operation of said translating device.

JAMES T. NEISWINTER.

